Aircraft heater with wick burner



July 20, 1948.

J. l. TRIMBLE arm, AIRQRAFI HEATER WITH wIcK- URNER Original Fiied March 2, 1945 M /7 l/y/ezii: d

attorney Patented July 20, 1948 AIRCRAFT HEATER WITH WICK BURNER 1 John I. Trimbleand William M; Myler, Jr., lumbus, Ohio, assignors, by mesne assignments,

to Surface Original application 477,746. Divided an The present invention relates to an air heater for use in aircraft and has for its object to embody in the heater a combustion unit which shall permit the volume rate or velocity of combustion supporting air supplied to the unit to be varied over a relatively wide range without danger of blow-out of the combustion flame. A combustion unit of this kind has special utility in a heater for use in aircraft for reasons presently appearing.

For a consideration of what we believe to be novel and our invention, attention is directed to the following specification and the claims appended thereto.

This application is a division of our abandoned application Serial No. 477,746, filed March 2, .1943.

In the drawing, the single figure is an axial section of the improved heater.

The improved heater comprises a cylindrical combustion chamber 1 formed by a cylindrical shell or barrel =8 which at its front end is closed by a head member or wall 2 and which at its opposite or exhaust end. is closed by an ordinary flat wall 3. The barrel is positioned in an elongate cylindrical casing 25 which defines a passage for the air to be heated. The casing 25 at its front end is closed by an ordinary end wall 26 from which there extends outwardly a relatively short air inlet pipe 21 adapted for connection with a main air supply line or duct 30 already installed in the airplane and which leads from an air scoop or the like so that the air pressure in the air line will ordinarily vary with the speed of the airplane. The heated air passes from the casing at its far end through an outlet 3| adapted for connection with a hot air distributing duct 32 already installed in the airplane. A damper 33 may be provided in said outlet 31 to control the effective discharge area of the latter.

The fuel and the air for supporting combustion thereof are separately introduced into the combustlon chamber I. The fuel, such as engine gasoline, is supplied to the front end of the combustion chamber by a non-combustible wick or porous body 6 in the for-m of a disk positioned within the barrel 8 next adjacent the front end closure 2. The wick is kept wet with liquid fuel by a small feed pipe l5 embedded therein, the pipe leading from a metering nozzle Ill carried by a fitting l6 which extends outwardly from the wall Of the barrel 8 opposite the rim of the wick. The fuel supply line leading to the metering nozzle is indicated at I. The fuel in the wick is initially heated to ignition temperature by a heating coil H which extends through and beyond Combustion Corporation, Ohio, a corporation of Ohio March '2, 1943, Serial No.

Toledo,

(1 this application March 21, 1946, Serial No. 655,933

3 Claims. (Cl. 158-28) 2. central aperture in, the wick, the coil being mounted on a plug 13 secured inafltting-M,

which extends outwardly from theend closure 2 A current carrying conductorv of the barrel 8.

for the heating coil is indicated at [2. The air for supporting combustionofythe-fuel enters the combustion chamber; l throughan air inlet 4 in the side ofthe barrelB at apont a short distance in advance of the wick. A stream of air is conducted to the air inlet by means comprising a conduitgfi which is tangent to said shell oribarrel 8 at said inlet so that the air on entering the combustion chamber will whirl therein and thereby impart a corresponding whirl to the advancing fuel and thus produce a whirling flame. By reason of the fact that the flame is caused to whirl by the incoming air, the volume rate or velocity of air thus supplied to the combustion chamber may be varied over a relatively wide range without danger of blow-out of the flame primarily because the increased linear velocity of the incoming air affects the whirling flame substantially only to the extent of increasing its rotational velocity without substantially decreasing the tendency of the flame due to its whirling to ignite and reignite the unburned fuel.

It will 'be understood that at high altitudes a greater volume of atmospheric air is required to burn a given weight of fuel than at low altitudes because of the decreased density of the air at high altitudes. However, if we assume that the present heater will ordinarily be installed in an airplane which will not normally operate at such high altitudes as to make changes in density of the atmospheric air an important factor in the operation of the heater, there remains the fact that it may be desirable to avoid the expense of an air pressure regulator in the air supply line leading to the air inlet 4 even though the air pressure may vary with the speed of airplane due to air being scooped from the atmosphere as is usually the case.

In the present heater, the combustion-supporting air from the main air supply line 30 is conducted to the tangential air conduit 5 through a passage which may include an air scoop 34 in the air receiving pipe 21 and a conduit 35 which leads from the scoop 34 to the conduit 5. A relief valve 36 in an extended portion of the intermediate conduit 35 vents air from the latter when the air pressure in the latter exceeds a predetermined maximum as determined by the setting of a spring 31.

Near its rear end closure 3, the barrel 8 has a side outlet IT for exhaust product's of combustion,

the outlet being in the form of a short pipe 22 which connects with an exhaust pipe 23 adapted for connection with an exhaust flue 24 already installed in the airplane. The air vented by the relief valve? may also flow It'ortheexhaust pipe 23 through anintermediate lengthiofconduit 40.

To reduce channeling of the hot combustion gases towards the exhaust port l1, provided in the barrel 8 in advanceeof the. waste gas outlet I! a disk-type bafil"2'0"spacedfrcm the walls of the barrel a's indicatedat: 2+ to: provide a ring-type exhaust passage?fon saidvgases.

It may be stated that the -heaater is' arelative ly small affair having a heat 15,000 B. t. u. per hour and that theinside diameter of the .barrel 8 will ordinariiygnot bein excess of four inches.

What is claimed as new is:

1. A heater comprising a heating unit for" heating a medium adapted to flow in heat exchange relation (therewith,- said unit comprising a cyllndiiical shell defining:air elongated cylindrical combusti'o'nizonei an; end 'wa'll closing the front emi of saidishellia: porous body disposed across said zone in front of saidi end' wall for"feedingi vaporized-liquid iuel to said 'z0ne,"-mean's' for feedin'g lihuidi-iieltb s'aid b'ody, means'for beatings aid body-to valsi'orize -the liquid fuel; means for ignitlfig 'the vEpenizedfuel; said cylindrical shell haviii'g airz aherture in its side for the entry-ofcombu'st'iim supporting air-mm: said zone near the there may be output of about" means for heating the body binationrwliichi'includes a relief valve adapted to ventair'fromthe said air conducting means when the airpressure'therein exceeds a predetermined maximum.

JOHN I. TRIMBLE. WILLIAM M. MYLER, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UN ITED- STATE-S1 PATENTS Number Name Date 135%;025 Sturgis' jMay 4; 1926' 21097255 Saha Oct. 26, 1937 2112391 Axionnaz; Mar. 29, 1938 23482422 Schaefler' May 9, 1944 213781781 McCo'llum June 19, 19245- 2,386,746 Hess Oct. 9, 1945' 

